Field of the Invention
The present invention relates to a harmonic drive capable of measuring an axial force generated from a wave generator thereof, thereby allowing output torque to be measured without a torque cell.
Description of the Related Art
Harmonic drives can improve certain characteristics of a motion translation compared to traditional gearing systems (such as helical gears or planetary gears). In general, a harmonic drive (also known as “strain wave gearing”) is generally made up of three basic components: a wave generator, a flex spline, and a circular spline. In a harmonic drive, the wave generator typically has an elliptical shape, and is installed inside the flex spline, and the flex spline in which the wave generator is mounted is installed on an inner circumferential surface of the circular spline. The inner circumferential surface of the circular spline and an outer circumferential surface of the flex spline are generally toothed in order to prevent sliding.
In these types of systems, it is important that the output torque be measured. Currently, this is done via the torque cell. However, as the output torque is increased, the rigidity of the torque cell increases as well. As such, a volume/weight of the torque cell should be increased as a result. In addition, an additional member for restricting the torque cell to one degree of freedom is required, and this also increases the volume/weight. Thus, since inertia of the output stage is increased, responsiveness of a system is degraded by the current measuring techniques.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.